Bed adsorption system

ABSTRACT

The invention relates to a method of distributing a liquid in the fluid bed of an up-flow or a down-flow fluid bed reactor. The invention provides efficient distribution and plug flow like fluid flow through the fluid bed where turbulence and/or back-mixing of the fluid are minimized. In accordance with the invention a fluid bed system for use in treating a fluid by contacting the fluid with a solid phase media is provided and the system includes a reactor chamber adapted to contain the solid phase media and at least one fluid distribution means adapted to distribute and/or deliver the fluid to be treated among the particles of the medium.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of, and claims priority under 35 U.S.C. §120 on,U.S. application Ser. No. 10/275,873, filed Jun. 20, 2003, now U.S. Pat.No. 6,977,046, which is a National Phase entry of PCT/DK01/00332 filedon May 10, 2001, which further claims priority under 35 U.S.C. §119 toDenmark 2000 00784, filed May 12, 2000, the contents of both of whichare incorporated by reference.

The present invention relates to a method of distributing a liquid inthe fluid bed of an up-flow or a down-flow fluid bed reactor.

FIELD OF THE INVENTION

The field of this invention is fluid bed reactors and methods fordistribution of fluid in fluid bed reactors to obtain efficientdistribution and a plug flow like fluid flow through the fluid bed whereturbulence and/or back-mixing of the fluid are minimised, such asavoided Particularly interesting is the field of expanded bed adsorptionand fluid bed reactors used for this purpose.

BACKGROUND OF THE INVENTION

Generally, a fluid bed reactor, may comprise a vertical reactor with aninlet, an outlet, a fluid bed of particles (a solid phase), and aliquid. The liquid is introduced at the inlet and dispersed, optionallythrough a gas head in case of down-flow reactors, on the bed of solidphase particles, which are suspended and fluidised by the liquid. Theliquid is conducted through the bed and a pool of reacted and/orunreacted fluid is let out at the outlet.

Up-flow fluid reactors have liquid inlet at or near the bottom of thereactor and solid phase particles of specific gravity larger than thatof the liquid.

Down-flow fluid bed reactors have liquid inlet at or near the top of thereactor and solid phase particles of specific gravity less than that ofthe liquid.

The suspended and fluidised solid phase particles may be impermeable tothe fluid or completely permeable to the fluid and substances present inthe fluid. The suspended and fluidised solid phase particles may furtherbe reactive or may carry immobilised reactive components selected forsolid phase chemical or physical processes with one or more componentsof the fluid in procedures such as enzymatic reactions; fermentation;ion-exchange and affinity chromatography; filtration; adsorption;chemical catalysis; immunosorption; solid-phase peptide and proteinsynthesis; and microbiological growth of micro-organisms.

In fluid bed reactors partially solving the problems of packed bedcolumns, i.e. the problems of suspended matter clogging up thesolid-phase bed which increases the back pressures and compresses thebed, disturbing the flow through the bed, the solid phase particles arekept in a free, fluid phase by applying a flow having an oppositedirection to the direction of the relative movement of the solid phaseparticles. Thus, solid phase particles having a density larger than theliquid and moving downwards due to gravity may be kept in a free, fluidphase by an upwards flow of liquid. Also, solid phase particles having adensity less than the liquid and thus moving upwards may due to buoyancybe kept in a free, fluid phase by a downwards flow of liquid.

In order to carry out solid phase chemical or physical processes in afluid bed reactor, an even and smooth distribution of fluid in the fluidbed without back-mixing is often desired. However, fluid bed reactorsknown in the art do not have efficient means known per se to avoidformation of channels as well as unwanted turbulence and back-mixing inthe solid phase particle bed. Especially when the task is to distributethe liquid in large industrial scale reactors (e.g. reactors withcross-sectional areas of more than 0.5-1 m²) it becomes increasinglydifficult to obtain a satisfactory distribution of the fluid.

An interesting field of application of fluid bed reactors is EBA.

EBA is an abbreviation for Expanded Bed Adsorption. This is a technologyused widely within the biotechnology industries, for example for theproduction of pharmaceuticals and diagnostic products and in particularfor the separation and purification of a broad range of bio-molecules,for example enzymes, proteins, peptides, DNA and plasmids from a vastrange of extracts and raw materials, many of which are crude andunclarified. The present invention particularly relates to a new way ofintroducing the fluid to be processed into an expanded bed adsorptioncontactor.

The term expanded bed is used to describe a special case of a fluid bed(or fluidised bed) where turbulence or back-mixing of the fluid in thesuspended bed of solid phase particles is at a minimum. Another term forthis situation is that the fluid passes the expanded bed With “plugflow” and thus resembles the flow pattern in a packed bed whereinturbulence and back-mixing are practically absent.

A traditional purification process for a mixture comprising one orseveral target molecules could be purification on a packed column (i.e.not EBA), however this requires multiple operational steps such asfiltration and centrifugation in order to ensure that impurities insuspension and particulates (for example colloids, whole cells, cellwalls, protein aggregates) are removed before the mixture is applied toa suitable packed column. These steps are necessary in order to avoidclogging of the packed column. In the packed column, a givenchromatographic medium is present for binding of molecule(s) which aregenerally the target of the purification, but alternatively can also beused for binding impurities. This chromatographic medium can be adaptedto various purification purposes.

The main principle in EBA is to keep the chromatographic mediumfluidised and thereby allow particulate impurities, suspended solids andcolloidal materials to pass through the column. By using the EBAtechnology, it is in many instances possible to avoid theabove-mentioned operational steps (i.e. those used before packed bedchromatography) before application of the raw material to the column. Inthis manner, time and expenses for these processes are reduced makingEBA a valuable technology, which is economically recommendable for thepurification of a large number of different bio-molecules. In addition,productivity and overall yield can be expected to be improved whencompared to traditional processing using packed beds.

In order to utilise the EBA technology, an EBA column used to contain asuitable chromatographic medium is required in conjunction with asuitable fluid distribution mechanism.

A brief presentation of the steps generally used in the EBA technologywill be given in the following (assuming it is an up-flow process withsolid phase particles more dense than the fluid).

-   -   1. An adequate quantity of solid phase adsorbent is placed in an        EBA column (i.e. the fluid bed rector).    -   2. Fluid flow through the adsorbent from below is initiated by        pumping the liquid to be processed through a fluid distributor.        The adsorbent is thereby fluidised (expanded).    -   3. The adsorbent is rinsed in the column and the conductivity        (i.e. salt concentration) and pH are adjusted to what is        required to allow binding of the target to the adsorbent.    -   4. Raw material (i.e. the feedstock) is applied to the expanded        bed of adsorbents and the target molecule(s) are bound.    -   5. The remaining raw material is rinsed out from the column        using a wash fluid.    -   6. The target molecule is eluted off the adsorbent medium by        applying a fluid that weakens the interaction with the        adsorbent. The elution of the target molecule may be performed        after packing the chromatographic adsorbent and reversing the        flow direction in the column or the elution may be performed in        the expanded bed state.    -   7. The chromatographic adsorbent is finally (optionally) rinsed        and regenerated.

Before the raw material is applied to the column, it should be ensuredthat expansion of the bed of adsorbent media is stable (i.e. that plugflow like fluid rise is obtained in the column without unwantedturbulence or back mixing of the fluid). The most reliable way ofchecking seems to be determining the number of theoretical plates byexamining the residence time distribution following addition of atracer. Such methods are well known to those familiar with examining theperformance of reactors and particularly to those versed in the art ofexpanded bed adsorption (for example see the hand book “Expanded BedAdsorption” by Pharmacia Biotech, Edition AA, page 14; or Levenspiel, O.1999. Chemical reaction engineering, 3^(rd) ed. John Wiley and Sons,Inc. N.Y.). A satisfying total number of theoretical plates in a columnindicating a low degree of back-mixing and fluid flow characteristicssuitable for an EBA process is generally in the range of 25 to 30 platesor more (see for example “Expanded Bed Adsorption” by Pharmacia Biotech,Edition AA, page 16). In addition, it is generally considered that50-100 theoretical plates per meter sedimented bed height issatisfactory. Furthermore, visual inspection of the bed particularlyusing dyes or colored tracers can provide valuable qualitativeinformation about the presence of channels or jet streams in the column.If the solid phase media move only in small circles, channels are notobserved and local jet streams of fluid largely devoid of media cannotbe seen, this is a good indication that the adsorbent media is expandedin a stable manner.

If an EBA column is not expanded in a stable way and has a plug flowfluid rise, the adsorption efficiency may be low and the whole processeconomy may be impaired. In analogy, the same will be true for a broadrange of other fluid bed and expanded bed reactions not related toadsorption e.g. (continuous) enzymatic reactions and chemical catalysis,chemical synthesis of e.g. peptides and polynucleotides. In these cases,an unstable expansion with turbulence and back-mixing may result in ahigh loss of unreacted chemical building blocks at the outlet of thecolumn and potentially a slower reaction rate. Also, chemical reactionequilibrium may not be reached or may shifted in an unfavourabledirection.

Further information about EBA technology can be found in the book“Expanded Bed Adsorption” by Pharmacia Biotech, Edition AA.

DESCRIPTION OF PRIOR ART

U.S. Pat. No. 4,032,407 discloses a tapered bed bioreactor applyingimmobilised biological catalysts or enzymatic systems on fluidizableparticulate support materials consisting of coal, alumina, sand, andglass, i.e. materials heavier than the fluid, particularly an aqueousfluid.

EP-A-0175568 discloses a three phase fluidised bed bioreactor processcomprising purifying effluents in a three phase fluidised bed comprisingsolid particles being made by mixing a binder with an inorganic materialbased on aluminum silicate, granulating the resulting mixture, andfiring the granules to sinter them. The specific gravity of the sinteredgranules is adjusted to fall into a specific range from 1.2 to 2.0 byvarying the mixing ratio of inorganic powdery materials based onaluminum and binders, said sintered granules having a diameter from 0.1to 5 mm.

EP-A-70025309 discloses a down-flow fluid bed bioreactor applying biotaattached to carrier particles consisting of cork, wood, plasticparticles, hollow glass beads or other light weight material and havinga specific gravity which is less than that of a liquid sprayed onto theupper part of a fluid bed of suspended carrier particles and conducteddownward through the bed.

A disadvantage of distributing an introduced liquid in a fluid bedreactor by simple spraying is the formation of channels in the bed byfluid streams.

EP-A-0005650 discloses an up-flow fluid bed reactor having fluidisingliquid flow distributors at the bottom thereof providing flow paths toavoid turbulence effects. Besides requiring complicated flow paths, agreat disadvantage of such a distributor is that it may be clogged byparticulate matter.

EP-A2-088404 discloses a fluid bed reactor system for catalyticpolymerisation of olefin monomers composed of a cylindrical reactionvessel equipped with distribution plate and agitator disposed in thefluidised bed above the plate and adapted to cause a rotational flow inthe fluidised bed, said distribution plate having many passage holeseach covered with a cap having an opening the direction of which varieswith the distance from the centre of the plate and faces the samedirection as the direction of the rotational flow. The fluid bed reactorsystem is intended to reduce various troubles such as blocking of thedistribution plate, formation of polymer agglomerates, and stagnation,adhesion, and agglomeration of polymer at the caps.

EP-A1-0007783 discloses a control system for preventing accumulation ofexcessive cellular material in a fluidised bed reactor comprising aseparator column having means to effect shearing of excess cellularmaterial from the particles to produce in the column a mixture ofsheared material and partially stripped carrier particles, said carrierparticles being returned to the bed while the sheared material isdischarged from the column through the draw-off port. In a specificembodiment the shearing is effected by an agitator arrangementcomprising a motor-driven mixing blade operating within the lowerportion of the separator column; to rotary speed of the mixing bladebeing adjusted to an optimum degree of shear for the cellular growth.Excessive pulverisation of the sheared material is avoided by using nota too high rotary speed.

Patent Abstract of Japan, Vol. 8, No. 162, C235 (Abstract of JP 59-62339) discloses a vertically movable agitator for gas fluidisationequipment to obtain an effective treatment of powder and granules.

EP-A2-0243845 discloses a fluid bed having a built-in device in form ofa perforated plate and/or net for performing gas-solid phase reactionswhereby generated voids are destroyed so that a homogeneous fluid bedwithout large voids is provided.

DK/EP 0538350 T3 discloses chromatographic adsorption particles havingcovalently bound thereto at least one active substance for binding ofmolecules in a liquid chromatographic fluid bed process. Theseadsorption particles are formed of a porous composite material withpores permitting access for the said molecules to the interior of thecomposite material. The spheres can be produced having a given densityand diameter. The density is controlled by incorporation of one or moreinert particles in the chromatographic medium, the number, material andpercentage of the inert particles being significant for the ultimatedensity of the chromatographic medium. In additions, the pore size canbe controlled. The density controlled particles can be viewed as inertheavy/light particles coated with a hydrophilic layer, a conglomerationcompound such as an agarose layer of different concentration and thuspore size.

The book “Expanded Bed Adsorption” by Pharmacia Biotech, Sweden,discloses that the size and density of the individual sphere at a givenflow situates the sphere at a specific position in the column. The smalland light spheres will move to the upper part of the expanded matrixwhile large, heavy particles will move towards the lower part. Theresult is that the particles settle at their ideal position after asuitable period of time. When this has taken place, expansion will bestable.

DK/EP 0538350 T3 further discloses a liquid bed reactor as adown/upflowing liquid fluid bed reactor comprising a vertical reactorcontainer with an inlet, an outlet, a fluidised particle bed ofchromatographic adsorbent particles and means for initiating movementwhich are located near by or in the fluidised particle layer which isclosest to the liquid inlet. There is a mixed zone, i.e. a stirringzone, the size of which is determined by the degree of stirring, theliquid flow and the quantity of matrix in the reactor container.Above/below this zone is a non-mixed zone in which a so-called plug flowis achieved. By the term plug flow is understood a movement of theliquid as a band through the container and consequently also through thematrix.

An example of such a reactor container is an UpFront column 20™ which isan up-flow reactor developed by UpFront Chromatography A/S, Copenhagen,Denmark.

This reactor container is constructed in such a manner that a supportingnet with a pore size of 50 μm is located at the bottom. Below thesupporting net is an outlet/inlet which is primarily used as an outletduring elution. A motor axis on which a stirrer is secured extends downthe middle of this net. The rate of the stirrer can be varied. Stirringonly occurs when the flow comes up through the column. During elutionthe stirrer is stopped. Right above the supporting net a side inlet islocated. Here, all liquid is supplied when the matrix is to be and hasbeen fluidised. This inlet can be opened and closed by siding the inletvalve into or out of the column pipe. The column pipe is a borosilicatepipe of 20 mm. The actual inflow takes place through four round openingswith a diameter of 3 mm each located in that part of the inlet valvewhich is inside the column pipe. The valve is closed at the end and thefour round openings are distributed in the same cross-section in twoaxes placed at an angle of 90 degrees to each other. The column pipe is50 cm long (high) and on its side is a scale so as to enable reading ofthe expansion of the matrix at any time. In addition, the column isprovided with a float adapter, an UpFront float, which provides a gentleand good distribution of the elution buffer during (down flow) elution.At the top is an outlet/inlet. Every inlet and outlet is provided withvalves on which suitable hoses are mounted. Buffer and raw materials arepumped into the column at an even flow. Typically, the matrix will be ⅓of the column height. In this case, it is possible to up expand the bedto 3 times. Depending on the type of particles/matrix applied, the flowcan vary from 6 column cm/min to 900 column cm/min.

The stirring zone varies from 2-20 cm. In this application the termstirring zone is to be understood as exactly the height in the column atwhich a stirring of liquid and matrix occur. The viscosity and flow ofthe liquid and the stirrer's design and rate are significant for theextent of the zone. In addition, it is important that the column isplumb (i.e. vertical). This concept can also be scaled-up to a largercolumn diameter.

WO 95/20427 discloses a construction for adsorption/desorption of asubstance where liquid can flow through a column of matrix. Thisconstruction comprises: a) a bottom adapter which is located at thebottom part of the container. The bottom adapter defines the bottom. Theadapter has an opening in the bottom for inflow/outflow of liquid to andfrom the bottom part of the container. This adapter also has adistribution function. It creates the back pressure necessary to createplug flow; b) a top adapter which is located at the top part of thecontainer. This adapter has an opening pointing towards the bottom forinflow/outflow of liquid to and from the top part of the container. Italso has a distribution function. This upper adapter has a densitypermitting that it floats on the liquid passing through the container.By means of hoses, both adapters can lead liquid to and from thecontainer depending on the direction in which the liquid should flow.

Pharmacia Biotech has developed an EBA column which distributes theliquid in another way than by stirring. In the bottom of the columnthere is an inlet/outlet. Above the column is a distribution platethrough which the liquid has to pass to enter the column. Thedistribution plate creates the pressure drop necessary to create a plugflow. By the term plug flow is understood the movement of the liquid asone front through the matrix. This bottom adapter leads the liquidvertically upwards through the column. The top adapter can be positionedanywhere necessary in the column. In this manner head space can bereduced. By the term head space is understood the liquid above thematrix.

A serious technical problem in connection with EBA columns using adistribution plate through which the fluid to be processed must pass, isfouling. This is particularly problematic when feedstocks containing forexample, whole cells, disrupted cells, particulates, nucleic acids orcolloidal materials are present and can lead to blockage of thedistribution plate. Another further technical problem is that thedistribution plate must have hole sizes small enough to prevent ingressof the solid phase support medium into the fluid distribution mechanismwhen fluid flow is stopped. This severely limits the lower size of solidphase supports that can be used for fluid treatment.

Although problems of fouling might be addressed by using larger(relative to those in a perforated plate distributor) fluid inlet portsin the column base or radially on the column wall and a local mixer todistribute the fluid, a serious technical problem in connection withsuch known EBA column using a stirrer is that when the column isscaled-up, scale effects begin to play a dominant role. This is mosteasily recognised by the presence of dead areas/volumes, i.e.areas/volumes where the solid phase medium is not properly contactedwith the fluid to be treated. This can lead to channels in the expandedbed and serious reductions in process performance as well asdifficulties for cleaning in place and support regeneration. In additionthe ability to create a small, localised, well-mixed area in the bottomof a column in the vicinity of the fluid inlet port(s) becomesincreasingly difficult as column diameter is increased.

BRIEF DESCRIPTION OF THE INVENTION

Thus, it is an aim of the present invention to provide a system and amethod at least seeking to solve the problems of using a stirring deviceto distribute fluid entering through large ports on the column wall orbase. Consequently, the present invention provides a fluid bed systemfor use in treating a fluid by contacting the fluid with a solid phasemedium, in a system which, in a first aspect, comprises:

-   -   a reactor chamber having an upper end and a lower end and to        contain the solid phase medium; and    -   at least one fluid distribution means adapted to distribute        and/or deliver the fluid to be treated among the particles of        the medium.

In particular preferred embodiment, the distribution means deliver(s)and distribute(s) the fluid to be treated through a rotating distributorwithout the need for significant stirring or mixing and which is placedamong the particles of the medium.

In accordance to the aim of the present invention, preferably for fluidbed and expanded bed columns, said distribution system uses preferablylarge fluid outlet holes compatible with foulants and which preferablyavoids generation of dead zones and which preferably provides even fluidcoverage of the cross sectional area of the column so that a plug flow,or substantial plug flow, like fluid rise is developed in the column.

According to the first aspect of the invention the fluid bed systemutilises, a distribution means preferably specifically designed tosimultaneously deliver and distribute the fluid to be treated among theparticles of the medium without the need for significant mixing. Therebythe present invention differs from prior art fluid bed system as allknown fluid bed systems deliver the fluid to be treated to the medium atthe column extremities. By applying the fluid to be treated at thecolumn extremities, the fluid must subsequently be distributed to theinterior of the bed of solid phase media to achieve a satisfactory flowprofile in the column and to ensure a good contact between the solidphase media and the fluid to be treated.

Design of a fluid distribution device to fulfil the aims stated abovehas been particularly difficult, especially when the column isscaled-up, as in many of the prior art distribution devices, thetransportation of the fluid occurs often in the main part by the actionof the stirrer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention, and in particular preferred embodimentsthereof, will be described in connection with use in an up-flow expandedbed adsorption column of 150 cm diameter and in connection with theaccompanying drawings and pictures in which:

FIG. 1 shows a close-up photograph of the distributor (the distributoris shown upside down),

FIG. 2. shows a further close-up photograph of the distributor (upsidedown) shown in FIG. 1, the distributor blades and the fluid outlet holesthrough which fluid passes from the distributor and into the column isshown.

FIGS. 3 and 4 show the distributor of FIGS. 1 and 2 (upside down).

FIG. 5 shows the distributor of FIGS. 1-4 (the distributor is shownupside up), i.e. in the orientation used for an up-flow column.

FIG. 6 shows the base part inside of the column,

FIG. 7 shows a close up photograph of the base part of the column ofFIG. 6 and more particular a close up of where the distributor fits onto the drive mechanism used to rotate the distributor, and the holeconnected to the fluid feeder system through which the fluid to betreated comes into the central chamber of the distributor before passingalong the distributor blades and out into the column.

FIG. 7 a shows a close up photograph of the intermediate part used tofix the distributor to the column base, yet allow its rotation. FIG. 7 ashows in details attachment of the intermediate part (45) by the use ofthe bolts (44) to the column base part. The presence of the lip seal(not seen in the figure) between the intermediate part fixed to thecolumn base and the circular base part (30) of the distributor permitsthe distributor to rotate whilst at the same time preventing fluid lossfrom the chamber or support ingress into the chamber.

FIGS. 8-15 show the distributor according to the present inventionarranged in the column with about 2 cm of gel (solid phase medium) inthe bottom. The distributor isn't turning. Furthermore, the figure showsthe zones of clearing caused by the fluid jets (water in the presentcase) moving the solid phase support off the surface of the column base.The volumetric fluid flow rate in FIG. 8 is 2000 L/h and is 5000 L/h inFIGS. 9-15,

FIG. 14 shows a close-up of the edge of the column and discloses how thefluid comes out from the distributor in a jet down to the base plate,sweeping the matrix off the column bottom and removing dead zonesunderneath the distributor.

FIG. 15 shows the distributor according to the present inventionarranged in the column. The distributor is rotating with 4 rpm. As canbe seen there are no discrete zones of clearing evident in FIGS. 10-14since the fluid is being distributed evenly over the column base by theslow rotation of the distributor.

FIG. 16 shows schematically one variation the distributor according tothe present invention.

FIGS. 17-20 show examples of use of the present invention.

FIGS. 21 and 22 Shows a photograph of an up-flow expanded bed columnaccording to the present invention.

FIGS. 23 and 24 show photographs of details of the bed column shown inFIGS. 21 and 22.

FIG. 25 shows a photograph of the bed column shown in FIGS. 21 and 22with parts taken out from the interior of the bed.

FIG. 26 shows a photograph of a control panel for controlling a bedsystem according to the present invention.

FIG. 27 shows in a graph the effect of flow velocity on bed expansion.Linear flow velocities of 200 to 452 cm/h were used, corresponding tovolumetric flow rates of 3,500 to 8,000 L/h.

FIG. 28 shows in a graph the effect of flow velocity on bed expansionwas investigated at different distributor rotation rates. Linear flowvelocities of 170 to 452 cm/h were used, corresponding to volumetricflow rates of 3,000 to 8,000 L/h. Distributor rotation rates were:Rotation rates of: (x) 0 rpm, (▪) 2.5 rpm; (□) 3.75 rpm; and (●) 7.5 rpmwere used.

FIG. 29 shows photographs of dye movement at the column wall taken atvarious times after addition of a dye pulse: (a) 9 s, (b) 30 s, (c) 60s, (d) 120 s, (e) 180 s, (f) 240 s, (g) 300 s, (h) 360 s, (i) 420 s.Rotation rate was 2.5 rpm, superficial linear flow velocity was 283 cmh⁻¹ (volumetric flow rate was 5000 L/h), settled bed height was 35 cmand expanded bed height was 53 cm. Direction of movement of thedistributor blades was from right to left.

FIG. 30 shows in a graph rate of dye band movement measured at thecolumn wall. Closed symbol: top of band; open symbols: bottom of band.The distributor was rotated at 2.5 rpm. Error bars indicate standarddeviations of three separate experiments.

FIG. 31 shows in a graph residence time distribution of a pulse ofacetone added through the distributor being rotated at 2.5 rpm,volumetric flow rate was 5000 L/h.

FIG. 32 shows in a graph the effect of distributor rotation rate on thedimensionless residence time distribution of an acetone tracer pulse.E_(θ) is the exit age distribution of acetone tracer based ondimensionless time (θ). The distributor was rotated at (rpm): (▪) 0, (□)2.5, (●) 3.75, (◯) 5, (▾) 7.5 and (Δ) 10.

FIG. 33 shows in a graph the effect on the numbers of theoretical platesin the column generated by the rotating distributor when water waspumped to give flow velocities in the column ranging from 170 cm/h to370 cm/h (3000 L/h to 6500 L/h).

Table 1 show examples of the use of the present invention. Bed voidagewas determined based on expanded bed height and assuming settled bedvoidage of 0.4. The voidage was then used to calculate the interstitialfluid velocity based on the observed time taken for tracer to passthrough the column or the rate of dye band movement at the wall (seeFIG. 30). The theoretical velocity was determined based on the expectedtime for a tracer to pass through the bed given the voidage, volumetricflow rate (5000 L h⁻¹) and expanded height. Values for interstitialfluid velocity observed, are averages and standard deviations of nseparate experiments.

Table 2 shows examples of the use of the present invention

GENERAL DESCRIPTION OF THE INVENTION

Referring to the accompanying figures the general principle of the fluiddistributor system according to the present invention will now bedescribed. As stated in the introduction to the invention, columnsconsidered herein are in general defined by at least a reactor chamber,typically being tubular shaped, limited at the lower end by a bottompart and limited at the upper end by a top part. Inside the reactorchamber a solid phase medium is placed together with a fluid forfludisation of the bed. The fluid to be treated is caused to flowthrough this medium by the distributor. The medium is considered to be asolid phase medium in the sense that the medium is insoluble (orsubstantially insoluble) in the fluid to be treated and the medium canbe impermeable or permeable to the fluid to be treated.

According to the present invention, the fluid to be treated is deliveredand distributed through a rotating device placed amongst among the mediaparticles. This is believed to be a novel and inventive feature whichprovides for a very efficient treatment of the fluid since the flowproperties desirable in the column for expanded bed adsorption aredeveloped.

In the preferred embodiment of the invention, the delivery anddistribution of the fluid to be processed is performed by a distributorcomprising a number of outlet holes for release of the fluid to beprocessed from inside the distributor to the solid phase media. Theseinlet holes are distributed in a plane (or planes) being perpendicularto the longitudinal axis of the tubular shaped reactor chamber, whichplane(s) is(are) situated in the vicinity of the bottom part of thereactor chamber in the case of an up-flow type reactor. In the case of adown-flow fluid bed reactor type, the plane (or planes) is(are) situatedin a distance (in distances) from the top part of the column—or belowthe free surface of the fludising liquid. In all cases the inlet holesare below the free surface of the fluid.

Furthermore, in case of an up-flow type reactor these holes are arrangedso the fluid is delivered/distributed to the medium in a direction beingtowards the bottom part, such as being downwardly inclined, for examplebeing inclined 45° downward with respect to the horizontal, preferablybeing inclined 90° downward with respect to the horizontal,—or ingeneral in a direction being opposite to the direction of the main flowdirection (defined by the direction of the volume flow) inside thereactor chamber. In the case of a down-flow fluid bed reactor type, thefluid is typically inlet perpendicularly to the main flow direction andtangentially to the periphery of the reactor chamber.

Even though the distributor shown in the preferred embodiment of theinvention is adapted to be rotated, rotation of the distributor may notbe carried out if so desired. In such situations, design of thedistributor may be done without paying attention to such a requirementand the distributor may the be given any desired shaped. For instance,the distributor may be designed as a grid made by tubes with holes fordelivery/distribution of the fluid.

The fluid to be treated is according to the present invention ingeneral, pumped out of the holes in the distributor and into the columnamong the media by use of a fluid feeder system.

In the prior art systems the fluid is typically inputted to the columnthrough inlet ducts provided in the bottom/top part of the column andthe fluid is typically distributed to the medium by agitating the mediumby use of a stirrer.

In other prior art systems, the fluid to be treated is inlet to thecolumn through a distributor plate arranged so the fluid is distributedacross the cross sectional area of the column under the distributorbefore flowing into the column, i.e. before the fluid contacts themedium.

Compared to these prior art systems a very well defined and controlleddistribution and delivery of the fluid is obtained by the presentinvention as the fluid flows out of the holes (which may be placed in adefined pattern) in the distributor among the particles of the solidphase medium. Since the hole pattern can be pre-defined the risk ofhaving dead regions in the medium is minimised. Furthermore since thesize of the diameter of the holes may be pre-defined, the risk offouling or clogging of the outlet holes is drastically reduced whencompared to prior art systems using perforated distribution plates. Inaddition since the direction of the outlet holes and the hole size maybe predefined, for example directed downwards, and the diameter of thedelivery tubes radiating from the central chamber of the distributor amyalso be predefined, ingress of the solid phase medium into thedistributor (for example when the fluid flow is stopped) can becontrolled. This provides the possibility of using a wide variety ofdiameters of solid phase media. Furthermore, the distribution anddelivery of the fluid to the medium may be enhanced by rotating thedistributor. Primarily this serves the purpose of distributing the fluidevenly across the cross sectional area of the column With only a minimumagitation of the solid phase medium. The second effect may be obtainedby setting the rotational speed of the distributor so that turbulence isnot generated.

DETAILIED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following a preferred embodiment of the present invention will bedescribed in detail using the example of a distributor constructed foran up-flow expanded bed adsorption column 150 cm in diameter.

In FIGS. 1-4 the distributor is shown upside down and out of the column.The distributor 10 comprises a number of elongated tubes 20 (in thepreferred embodiment the distributor has twelve such tubes) evenlydistributed along the periphery of a circular shaped base part 30. Eachtube 20 is hollow. Furthermore, each tube 20 has holes 22 enabling fluidflow, at least, out of the tube 20. Please note that the holes 22 areprovided so that fluid exiting the tubes through these holes 22 will bedirected downward when the distributor is situated in the column (thedistributor pictured is shown upside down). In the preferred embodimentthe tubes 20 also have at least one hole 22 provided at the distal end,which releases some of the fluid in a direction preferably being in thelongitudinal direction of the tube 20 and also directed downwards, tosweep the corner of the column base plate and Wall.

The tubes 20 according to the preferred embodiment have circular crosssections, but the tubes 20 may be manufactured in other shapes. Since inthe preferred embodiment it is desired to minimise mixing and turbulencecreate by distributor rotation, and only to distribute the fluid overthe cross sectional area of the column, the tubes 20 may be given ashape so as to avoid mixing when rotated, for example a thin knife-likeshape or a tear-drop shape. If for some reason it is desired to obtainmixing, the cross sections of the tubes may be aerodynamically shaped,i.e. shaped such as to provide lift and drag to move the fluid and orthe solid phase support. Furthermore, the tubes 20 may be inclineddownward with respect to the horizontal to modify the fluid flow withinthe column.

In FIG. 16 the distributor 10 is depicted schematically. The elongatedtubes 20 are sketches with thick lines and the holes 22 are indicated byfilled circles. The thin and broken lines indicate that the distributor10 is circular and symetrical. Furthermore, the physical dimensions ofthe distributor 10 are indicated, for instance the exterior diameter ofthe distributor is indicated to be approximately 1400 mm and thediameter of the holes 22 are indicated to be 3 mm.

From FIG. 16 it is realised that the tubes 20 are identical and evenlydistributed around the circular shaped base part 30, but havingdifferent longitudinal distributions of the holes 22. As indicated (bynumbers in circles placed at the distal end of the tubes 20) in thefigure, four different longitudinal distributions of holes 22 areapplied to the elongated tubes 20. The distribution of the holes aredone so as to obtain an even distribution/delivery of the fluid amongthe particles of the medium and particularly an even distribution offluid over the cross sectional area of the column base. It can howeverbe envisaged that alternative hole diameters and hole placements mightbe used.

The holes 22 a placed at the distal ends of the tubes 20 direct thefluid in other directions than the holes placed along the tubes. Morespecifically, these holes 22 a whereof one is applied to each tube 20are arranged/shaped so that the fluid is directed in a direction beingaligned with the longitudinal direction of the tube 20 but in thepreferred embodiment of the invention the hole is directed at an angledownwards towards the base plate.

In FIGS. 1, 3 and 4 it can be seen that the circular base part 30comprises a cavity 32 (the purpose of which will be described in detailbelow) which the tubes 22 open into. At the centre of the circular basepart 30 a shaft 34 is provided, which shaft 34 adapted to link with adriving shaft 40 for turning the distributor 10, if such turning isdesired.

In the base part of the column, in which the distributor is intended tobe used, the driving shaft 40 for driving the distributor is located.Furthermore, a single fluid inlet 42 of a fluid feeder system isprovided in the base part of the column. In the preferred embodiment ofthe invention, this fluid feeder system is a single pipe containing afluid non-return valve (preventing back flow of fluid). This fluidfeeder system is the device which feeds the fluid to be treated (in thecolumn) into the distributor 10. During use, the feeder system isconnected to an external fluid source and the fluid is is preferablytransported through the feeder system by use of a pump appropriateconnected to the fluid feeder system. However it can be envisaged thatin a variation of the invention, fluid may enter the cavity 32 throughmore than one fluid inlet 42 connected to one or more fluid feedersystems.

After the fluid leaves the fluid inlet 42 it enters into the cavity 32and is distributed to the elongated pipes 20 and is finally deliveredand distributed among the particles of the solid phase medium throughthe holes 22. In the preferred embodiment, the fluid enters the cavity32 asymmetrically. In order to avoid uneven distribution of the fluid tothe tubes (20), in the preferred embodiment shown here, the cavity 32has a small volume leading to a high pressure of fluid within the cavityand within the tubes 20 so that the volume of fluid flowing out of theholes in the tubes 20 is substantially even. In a variation of thedistributor it can be envisage that the fluid to be added to thedistributor may be applied through the central drive shaft.

The cavity 32 is sealed to the base part of the column in order toprevent fluid from entering or leaving the cavity 32 in other ways thanthrough the fluid inlet 42 or the openings of the tubes within thecavity, respectively. The sealing device used must permit thedistributor to be rotated and ideally should permit the distributor tobe removed from the column base plate for inspection, servicing,cleaning or replacement. An intermediate part, shown in close up in FIG.7 a, is attached to the base part of the column by use of bolts screwedinto the threaded holes 44 shown in FIG. 6. This intermediate part iscollar shaped having the same external diameter as the circular basepart 30 and the same internal diameter as external diameter of thecavity 32. Sealing between the abutment surface of the circular basepart 30 and the abutment surface of the intermediate part is provided bya lip seal arranged in grooves provided in these surfaces (the groove inthe circular base part 30 is shown in FIG. 1 and is referenced bynumeral 38) and allows rotation of the distributor.

The distributor 10 is fixed to the driving shaft 40 by use of a boltpenetrating the circular base part 30 for engagement with a threadedbore 42 provided in the driving shaft 40.

An example of an up-flow expanded bed column comprising a distributoraccording to the invention is shown in FIG. 21. With reference to FIG.21 the column comprises:

-   -   a base plate on adjustable feet 101 (to adjust the column into a        vertical position),    -   an inlet tube 102,    -   an inlet valve connected to a rotating joint. 103,    -   a motor for rotating the distributor 104,    -   a hollow shaft 105 (not visible) connected to the rotating joint        and penetrating the base plate through the motor.    -   a central distribution chamber 106, distributing the incoming        liquid into 8 hollow tubes. The distribution chamber and the        tubes are rotated and the incoming liquid is distributed on the        surface of the base plate through holes pointing downwards.    -   a column tube 107,    -   a solid phase matrix 108, expanded by the up-ward flow of liquid        to position xx    -   a mixing zone with intensely mixed solid phase matrix and        incoming liquid 109    -   a plug flow zone without back-mixing 110    -   a liquid interface without solid phase matrix 111    -   a floating outlet unit 112 collecting the liquid from the        periphery of the outlet unit through holes, yy, into a central        outlet tube (extendible) leaving the column through a top plate.

While a slow rotation of the distributor in general is preferredaccording to the invention, it is in many instances also preferred thatthe rotational direction is reversed within certain time intervals.Especially in large diameter columns (e.g. ∅>30 cm) such a reversal ofthe rotational direction (i.e. from clockwise rotation to counterclockwise direction and vice versa) will prevent the expanded bed ofsolid phase matrix in engaging in a rotational movement that may extendall the way to the top of the expanded bed (and in some instances createa wave like movement of the entire bed).

The time lag between each reversal of the rotational direction may varywithin broad limits such as from a few seconds to several minutesbetween each reversal. The reversal as well as the rpm of thedistributors rotational movement may be controlled by an electroniccontrol box comprising the necessary electronic components to performsuch control of the motor working on the distributor. In connection witheach reversal the acceleration of the motor may be slowed down tominimise the mechanical stress on the distributor arms and the solidphase matrix as well as minimising any disturbance/mixing effects on theplug flow above the distributor which might occur by an abrupt change ofrotational direction.

Use of the Invention in an Expanded Bed Adsorption Column

EXAMPLE 1

The following example illustrates the effect of using a rotatingdistributor as described above, comprising an arrangement of hollowsteel tubes fitted with fluid outlet holes in an EBA column having adiameter of 150 cm. In this example the effect of flow rate on bedexpansion is demonstrated.

Procedure

The rotating fluid distributor system described above was fitted to theEBA column by using bolts in the threaded holes (44: see FIG. 6) to fixthe intermediate part (see FIG. 7 a) onto the stainless steel baseplate. The EBA column itself was specially constructed using atransparent material—PVC—so that the performance of the distributorcould be monitored visually. The PVC column contained no internalprotrusions, furthermore the base plate of the column was completelyflat as can be seen in FIG. 6 and FIG. 7. The EBA column containing thedistributor was initially filled with a suspension of a solid phasemedium in water. The solid phase medium was a non-derivatisedagarose/glass conglomerate (UFC Agarose beads D, product number 6902,UpFront Chromatography AIS, Denmark) having a bead density of approx.1.5 g/ml and a particle size distribution between 100-300 μm indiameter). In total about 620 litre of the solid phase medium was loadedto the column by pumping the suspension of the solid phase medium(matrix) through a valve in the bottom of the column. After loading ofthe solid phase suspension the matrix beads were allowed to settle(sediment) on the bottom of the column (i.e. no pumping of fluid intothe column). After sedimentation for about 15 minutes the settled bedheight was measured to be 35 cm.

Following this, water with a volumetric flow rate of 5000 l/hour waspumped into the column through the distributor according to theinvention.

In the initial phase the distributor was not rotating in order to ensurethat the solid phase medium was first somewhat fluidised (loosened up)in the vicinity of the steel tubes (the elongated tubes 20) of thedistributor. During this procedure it was observed that water wasflushing through the holes present in the end of the steel tubes and astrong jet stream pointing out against the column tube wall and floorcould be seen. It was not possible to observe; the flow of water throughthe holes present further into the column due to the presence of thesolid phase medium. After the initial flushing with water thedistributor was engaged to rotate with a relatively low speed of 2.5rotations per minute (2.5 RPM).

During a time period of 5-10 minutes the solid phase medium graduallyraised (expanded) in the column until an expanded bed height of 53 cmhad been reached. At this point no further expansion of the solid phasewas observed in the column (corresponds to a degree of expansion of53/35=1.5). Thereafter, the flow rate was changed to between 3500 to8000 L/h. The expanded bed height was then measured and the bedexpansion factor was calculated as the ratio of the expanded bed heightto the settled bed height. A linear relation between bed expansionfactor and flow rate was seen (FIG. 27), indicating that the fluiddistributor evenly distributed the fluid over the cross sectional areaof the column. If fluid distribution was poor leading to channeling, thebed would not expand sufficiently, and curvature of the expansion curveseen would be expected.

EXAMPLE 2

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested for generation of a stableexpanded bed by examining the effect of distributor rotation rate on bedexpansion.

The bed was fluidised as described in example 1 and then the expandedbed height was measured at different combinations of flow rate anddistributor rotation rate. The bed expansion factor was then calculatedas the ratio of expanded bed height to settled bed height. When thedistributor was not rotated, bed expansion was poor. (FIG. 28)demonstrating that rotation of the distributor is required to give thebest bed expansion. No significant changes in the degree of expansionwhere observed by using a distributor rotation rate of 2.5 rpm to 10 RPM(FIG. 28). The result suggests that even fluid distribution was providedby the distributor when rotated at a wide range of rates and suggests alarge window of operation is possible. Adequate and stable bed expansionis necessary to provide adequate voidage in the column (i.e. spacebetween the solid phase supports) so that when particulate containingfeedstocks are processed, the bed will not be clogged up.

EXAMPLE 3

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested to examine the flow resultingin the column by visualising fluid flow via the use of dye tracers.

The bed was fluidised as described in example 1 at a volumetric flowrate of 5000 L/h and the distributor was rotated at 2.5 rpm. Usingprocedures commonly known to those involved in the art of expanded bedadsorption, a volume of 200 ml of a solution of freshly preparedbromophenol blue (10 g/L in 1 M NaOH) was prepared and then added to thecolumn through a sample loop whilst the bed was fluidised with tap waterat a flow rate of 5000 L/h. The location of dye near the column wall wasthen documented by taking photographs. It was observed that when dyefirst entered the column, a jet of dye penetrated to the corner of thewall and base plate (FIG. 29 a) demonstrating that the fluid coming outof the outlet holes of the distributor was successfully directeddownwards and was able to move the solid phase support from underneaththe distributor. After 30 s a discrete band of dye was formed in alocalised area at the bottom of the column and no areas without dyecould be seen, demonstrating that dead zones underneath the distributorwere not present (FIG. 29 b). The dye band then progressed up thecolumn, maintaining its integrity as a discrete band and demonstrating aplug flow like fluid regime was created by the fluid distributor (FIGS.29 c to 29 l). A plug flow like fluid rise in the column suggests thatback mixing and axial dispersion is low which is necessary for asuccessful EBA process.

EXAMPLE 4

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested to examine the flow propertiesproduced in the column by comparing dye movement at the column wall andin the centre part of the expanded bed. The flow rate of fluid betweenthe expanded solid phase support, is called the interstitial fluidvelocity and this was determined in two separate types of experiments.The results were then compared to determine more carefully if fluidchanneling or dead zones were present in the column.

Dye was added to the column as described in example 3 and then thedistance from the column base plate to the top of the band was recordedat the column wall. The results in FIG. 30 show that the top of the bandmoved at a constant rate of 468 cm/h (which is equivalent to theinterstitial fluid velocity) up the column. The pattern of dyebreakthrough at the bed surface was then examined by removing the columntop piece and adding a dye pulse to the column through a sample loop asdescribed in example 3 and observing dye appearance at the expanded bedsurface. It was found that the dye broke though the bed surface in alarge circle approximately 100 cm in diameter, 335 seconds after dyetracer was added to the column. This equates to a dye movement rate, andan interstitial fluid movement rate of 570 cm/h in the central part ofthe column. The voidage of the bed can be calculated by those skilled inthe art of expanded bed adsorption when the expanded bed height isknown, the settled bed height is known and assuming a settled bedvoidage of 0.4. From the determined bed voidage, the theoretical rate oftravel of the dye can be determined. The results in table 1 demonstratethat dye at the centre part of the column moved slightly faster thanpredicted from theory and that at the wall moved slower. Thisdemonstrates that the distributor gives a parabolic flow profile in thecolumn, which is suitable for expanded bed adsorption and also suggeststhat any channeling in the column is low and not at a level likely tocause serious impairment of the column performance.

EXAMPLE 5

The rotating distributor and the column with solid phase media asdescribed in example 1 was further tested for the ability to generate aflow pattern suitable for expanded bed adsorption by determination ofthe number of theoretical plates per meter (residence time distributionmeasurement, RTD). The negative step input method as described in thehand book ‘Expanded Bed Adsorption’ by Amersham Pharmacia Biotech,Sweden, and which is commonly used by those skilled in the art ofexpanded bed adsorption was used for assessing the performance of thesystem.

A solution of acetone (0.5% in water) was pumped into the column with aflow rate of 5000 l/hour and the breakthrough of acetone at the outletof the column was followed by continuous measurement and recording ofthe absorbency of the fluid at a wavelength of 280 nm (UV light). Whenthe acetone was coming out of the column with a constant concentrationaccording to the UV signal, the fluidising solution was switched fromacetone back to water. The washing with water was performed with thesame flow rate of 5000 l/hour. Washing the column with water wascontinued until all acetone was washed out according to the recorded UVsignal, the experiment was stopped and the number of plates per meterwas calculated/determined from the recorded UV signal.

The result of the experiment indicated that the rotating distributor andthe fluid bed system had a plate number (N) of: N=103 per meter settledbed of solid phase support, which is indicative of a system with a lowamount of back-mixing and turbulence and indicates performance suitablefor expanded bed adsorption.

The fact that such a high plate number is obtainable with such a largecolumn diameter creates an expectation that even columns with diametershaving diameters in the range of 2-5 meter will work using thisprinciple of distributing the fluid.

EXAMPLE 6

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested for suitability of thedistributor to create appropriate flow conditions in the column by usingresidence time distribution experiments based on the pulse signalmethod. The theory behind this method is described by Levenspiel(Levenspiel O. 1999. Chemical reaction engineering, 3^(rd) ed. JohnWiley and Sons, Inc. N.Y.) and is commonly used by those skilled in theart of expanded bed adsorption for assessing the performance of thesystem. Briefly, in this technique a pulse of tracer is added that doesnot interact with the solid phase support in the column and the releaseof tracer from the column is monitored. According to Levenspiel (1999),the resulting concentration versus time curve is then converted to aresidence time distribution based on dimensionless time (E_(θ)) andplotted against dimensionless time (θ) and the results evaluated usingthe dispersion or tanks in series models. Using this technique it iscommonly known by those skilled in the art that the total number oftheoretical plates in an expanded bed column should be in the vicinityof 25 to 30 (see for example the hand book ‘Expanded Bed Adsorption’ byAmersham Pharmacia Biotech, Sweden).

In this example, for the residence time distribution (RTD) studies, a30.9 cm high bed of settled solid phase media was fluidised with waterat a flow rate of 5000 L/h using the distributor being rotated at 2.5rpm. Freshly prepared acetone in water (600 ml, 50% v/v) was appliedthrough the distributor to the column via a sample loop. A small stream(approximately 60 L h⁻¹) was split from the column outflow tube andpassed via a peristaltic pump to a UV-1 detector (Amersham PharmaciaBiotech, Uppsala, Sweden) fitted with an industrial flow cell and a 280nm filter. The output signal from the detector was captured every 10seconds using Baseline 810, version 3.30, data acquisition software(Dynamic Solutions Division, Millipore, Bedford, Mass., USA). Thedetector output resulted in a bell shaped curve which was normalised tounity and then converted to a dimensionless exit age distribution curve(E_(θ)) based on dimensionless time (θ). Using standard techniques, thedimensionless variance of the RTD was used to determine the coefficientof axial dispersion (D_(ax)) and the number of theoretical plates (N).The result in FIG. 31 demonstrates a bell shaped curve with good symetryaround the dimensionless time point (θ) of 1. This combined with thelack of excessive tailing of the curve suggests a low amount ofchannelling in the bed and a low degree of backmixing and axialdispersion (D_(ax)). The RTD curve gives a D_(ax) value of 6.08×10⁻⁶m²s⁻¹ and a theoretical plate number of 29.4, equivalent to 95 platesper meter of settled bed, which agrees closely with the result ofexample 5 (above). The number of plates in the column and thecoefficient of axial dispersion closely approximates the performancereported for much smaller columns of 60 cm diameter (equipped with afoulant susceptible perforated plate distributor) (see for exampleHjorth R. Leijon P. Barnfield Frei AK, Jägersten C. 1998. Expanded bedadsorption chromatography. In: Subramanian G (ed.) Bioseparation andbioprocessing. Wiley VCH, Weinheim: 199-226).

EXAMPLE 7

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested for suitability of thedistributor to create appropriate flow conditions in the column by usingresidence time distribution experiments based on the pulse signal methodas described in example 6. In this example, the effect of distributorrotation rate on the column performance was examined.

The experiment was conducted as described in example 6, but in additionthe residence time distribution of acetone was measured when thedistributor was rotated at a number of different rotation rates. Theresults in FIG. 32 demonstrate only a small effect of changes indistributor rotation rate and highlight the robustness of the fluiddistribution mechanism. The necessity for rotating the distributor canbe clearly seen in FIG. 32. If the distributor is not rotated,channelling is observed by the early breakthrough of the tracer andexcessive tailing of the RTD curve. The suitability of the distributorfor expanded bed adsorption is further demonstrated (See table 2) whenthe number of theoretical plates and coefficient of axial dispersion aredetermined from the results in FIG. 32.

EXAMPLE 8

The rotating distributor and the column with solid phase medium asdescribed in example 1 was further tested for suitability of thedistributor to create appropriate flow conditions in the column by usingresidence time distribution experiments based on the pulse signal methodas described in examples 6 and 7. In this present example, the effect onthe column performance of changes in flow rate of fluid applied by thedistributor was examined. The robustness of an EBA process to changes inflow rate is important since high flow rates may in general be preferredto give higher productivities in the column. However lowering of theflow rate may at times be required to control bed expansion, especiallyif a viscous feedstock is being treated.

The experiments were conducted as in example 6 except that two differentdistributor rotation rates were used: 3.75 rpm and 7.5 rpm and theresidence time distribution of acetone tracer was measured at differentflow rates of water being applied to the column. The residence timedistribution curves that were obtained were used to calculate the numberof theoretical plates. The results in FIG. 33 demonstrate the remarkablerobustness of the fluid distribution means with respect to columnperformance between flow rates of 4000 L/h and 6000 L/h when thedistributor is rotatated at 3.75 rpm. When a rotation rate of 7.5 rpm isused, the column performance is lower at flow rates between 4000 L/h and6000 L/h, however at low flow rates the number of theoretical plates ishigher than at 3.75 rpm. This result demonstrates an important aspect ofthe distribution design, namely the ability to improve fluiddistribution by modulating the rotation rate of the distributor.

1. An expanded fluid bed system for use in treating a fluid bycontacting the fluid with a solid phase media contained in the expandedfluid bed system which system comprises: a reactor chamber having anupper end and a lower end to contain the solid phase media and at leastone fluid distribution means adapted to be rotated and to distribute anddeliver the fluid to be treated among the particles of the medium, in asubstantially uniform manner over a cross sectional area of the fluidbed system, which system is sized and dimensioned to operate under plugflow conditions, wherein said fluid distribution means includes a numberof elongated tubes extending radially outwards towards an outerperiphery of the reactor chamber; each elongated tube has penetrationsextending from the inside of the tubes to the outside thereof so thatthe fluid to be treated flows through the internal of the tubes via thepenetrations and to the medium, and wherein said tubes have crosssections shaped, so that generation of turbulence induced by saidrotation is avoided, when the fluid distribution means is rotated withan rpm lower than
 10. 2. A fluid bed system according to claim 1,wherein the at least one fluid distribution means is placed inside thereactor amongst the solid phase media and through which the fluid to betreated is delivered and distributed.
 3. A fluid bed system according toclaim 1, further comprising rotating means for rotating the fluiddistribution means during distribution/deliver of the fluid so that thefluid is distributed/delivered substantially uniformed, or uniformed, ina zone of the medium when observed during a characteristic time.
 4. Afluid bed system according to claim 3, wherein the fluid distributionmeans comprises a central chamber into which the fluid to be treated ispumped and the at least one hollow elongated tube extends radiallyoutwards from the center of the distributor chamber towards an outerperiphery of the reactor chamber.
 5. A fluid bed system according toclaim 3, wherein each of the at least one elongated tube is or is not becompletely sealed at the end.
 6. A fluid bed system according to claim1, wherein at least some of the penetrations are orientated/shaped insuch a manner that the fluid exits the penetrations in a direction beingdownwardly inclined.
 7. A fluid bed system according to claim 6, whereinthe fluid exits the penetrations in a direction being inclined 45°downwardly with respect to the horizontal.
 8. A fluid bed systemaccording to claim 6, wherein the fluid exits the penetrations in adirection being inclined 90° downwardly with respect to the horizontal.9. A fluid bed system according to claim 1, wherein the radius or thehydraulic radius, defined as the ratio of the cross-sectional flow areato the wetted perimeter, of the penetrations is such as to preventsubstantial plugging or choking of the penetrations.
 10. A fluid bedsystem according to claim 9, wherein substantial plugging or choking ofthe penetrations is prevented by the fluid to be treated.
 11. A fluidbed system according to claim 1, wherein the radius or the hydraulicradius is between 0.5 mm and 1.0 mm.
 12. A fluid bed system according toclaim 1, wherein at least some of the penetrations are orientated/shapedin such a manner that at least some of the fluid exits the penetrationsin a direction being perpendicular to the main flow direction in thereactor chamber.
 13. A fluid bed system according to claim 12, whereinthe fluid exits the penetrations in a horizontal direction.
 14. A fluidbed system according to claim 1, wherein the inclination is measured asseen from a co-ordinate system rotating along with the fluiddistribution means.
 15. A fluid bed system according to claim 1, furthercomprising equalisation means adapted to equalize thedistribution/delivery of the fluid to the solid phase media.
 16. A fluidbed system according to claim 15, wherein the equalization meanscomprises a cavity through winch the fluid flows before entering into atleast one elongated tube.
 17. A fluid bed system according to claim 15,wherein the equalisation means is elongated tubes which have a constantor changing diameter over their length, combined with a distinctposition and/or size of penetrations in the tubes to provide asubstantially even fluid coverage of the cross sectional area of theswept area of the column base during a characteristic time when thedistributor is rotated.
 18. A fluid bed system according to claim 1,further comprising a fluid feed system adapted to feed the fluid to thedistribution means.
 19. A fluid bed system according to claim 1, whereinthe fluid distribution means is arranged so that fluid distributionand/or deliver occurs at the lower end, or in the vicinity thereof, ofthe reactor chamber.
 20. A fluid bed system according to claim 1,wherein the fluid distribution means is arranged so that fluiddistribution and/or deliver occurs at the upper end, or in the vicinitythereof, of the reactor chamber, such as in the vicinity of the freesurface of the fluidizing fluid.
 21. A fluid bed system according toclaim 1, wherein the bed system is an adsorption bed system.
 22. A fluidbed system according to claim 21, wherein the adsorption bed system isan Expanded Bed System.
 23. A fluid bed system according to claim 1,wherein the medium is a chromatographic medium.
 24. A fluid bed systemaccording to claim 1, wherein the fluid distribution means is adapted todeliver and/or distribute the fluid so as to fluidize the medium.
 25. Afluid bed system according to claim 1, wherein the solid phase medium isan adsorption medium and wherein the fluid bed system is used to removeone or more components from the fluid by an adsorption process in whichthe fluid is contacting the adsorption medium.
 26. A fluid bed systemaccording to claim 1, wherein the distribution means is adapted torotate during distribution/delivery of the fluid to be treated.
 27. Afluid bed system according to claim 26, wherein the distributor isadapted to rotate with a rotational speed in the range of 1-5 rpm.
 28. Afluid bed system according to claim 27, wherein the distributor isadapted to rotate with a rotational speed in the range of 2-4 rpm.
 29. Afluid bed system according to claim 27, wherein the distributor isadapted to rotate with a rotational speed of 3 rpm.
 30. A fluid bedsystem according to claim 26, wherein the distribution means is adaptedto rotate alternately clockwise and counter clockwise.
 31. A fluid bedsystem according to claim 30, wherein the time lag between each reversalof the rotational direction is smaller than 1 seconds.
 32. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 2 seconds.
 33. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 5 seconds.
 34. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 15 seconds.
 35. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 30 seconds.
 36. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 1 minute.
 37. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 1.5 minutes.
 38. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 2 minutes.
 39. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 3 minutes.
 40. A fluid bedsystem according to claim 31, wherein the time lag between each reversalof the rotational direction is smaller than 5 minutes.
 41. A fluid bedsystem according to claim 1, wherein the system is adapted to have thefluid to be treated a liquid.
 42. A fluid bed system according to claim1, wherein the system is adapted to have the fluid to be treated a gas.43. A fluid bed system according to claim 1, wherein the fluid bedsystem is an up-flow fluid bed system/reactor.
 44. A fluid bed systemaccording to claim 1, wherein the fluid bed system is a down-flow fluidbed system/reactor.
 45. A fluid bed system according to claim 1, whereineach elongated tube has penetrations that are bores.
 46. A fluid bedsystem according to claim 1, wherein the radius or the hydraulic radiusis between 1.0 mm and 2.0 mm.
 47. A fluid bed system according to claim1, wherein the radius or the hydraulic radius is between 2.0 mm and 3.0mm.
 48. A fluid bed system according to claim 1, wherein the radius orthe hydraulic radius is between 3.0 mm and 5.0 mm.
 49. A fluid bedsystem according to claim 1, wherein the radius or the hydraulic radiusis up to 7 mm.